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  <div class="question_difficulty">
   难度：Easy
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  <div>
   <h1 class="question_title">
    507. Perfect Number
   </h1>
   <p>
    We define the Perfect Number is a
    <b>
     positive
    </b>
    integer that is equal to the sum of all its
    <b>
     positive
    </b>
    divisors except itself.
   </p>
   Now, given an
   <b>
    integer
   </b>
   n, write a function that returns true when it is a perfect number and false when it is not.
   <p>
    <b>
     Example:
    </b>
    <br>
   </p>
   <pre>
<b>Input:</b> 28
<b>Output:</b> True
<b>Explanation:</b> 28 = 1 + 2 + 4 + 7 + 14
</pre>
   <p>
    <b>
     Note:
    </b>
    The input number
    <b>
     n
    </b>
    will not exceed 100,000,000. (1e8)
   </p>
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   <h1 class="question_title">
    507. 完美数
   </h1>
   <p>
    对于一个&nbsp;
    <strong>
     正整数
    </strong>
    ，如果它和除了它自身以外的所有正因子之和相等，我们称它为&ldquo;完美数&rdquo;。
   </p>
   <p>
    给定一个&nbsp;
    <strong>
     正整数&nbsp;
    </strong>
    <code>
     n
    </code>
    ，&nbsp;如果他是完美数，返回&nbsp;
    <code>
     True
    </code>
    ，否则返回&nbsp;
    <code>
     False
    </code>
   </p>
   <p>
    &nbsp;
   </p>
   <p>
    <strong>
     示例：
    </strong>
   </p>
   <pre>
<strong>输入:</strong> 28
<strong>输出:</strong> True
<strong>解释:</strong> 28 = 1 + 2 + 4 + 7 + 14
</pre>
   <p>
    &nbsp;
   </p>
   <p>
    <strong>
     注意:
    </strong>
   </p>
   <p>
    输入的数字&nbsp;
    <strong>
     <code>
      n
     </code>
    </strong>
    不会超过 100,000,000. (1e8)
   </p>
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